Windows Process Creation: VMware Horizon Log4j RCE Attempt via ws_TomcatService to cmd/powershell

Alert on ws_TomcatService.exe spawning cmd.exe or PowerShell on Windows as suspicious exploitation activity.

FreeReviewedSigma · High · v5

Product: windows
Category: process_creation
Author: @kostastsale (SigmaHQ), DRL 1.1
Published: 2022-01-14
Updated: 2026-07-31

ATT&CK techniques

Initial Access

Recon
Resource Dev
Initial Access
- T1190Exploit Public-Facing Application
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags process creation events where the parent process is ws_TomcatService.exe and the child process is cmd.exe or powershell.exe. Such behavior can indicate an attacker triggering initial execution from a vulnerable VMware Horizon component, consistent with attempts to achieve remote code execution through Log4j exposure. It relies on Windows process creation telemetry capturing ParentImage and Image paths.

Reporting behind it

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Windows Process Creation: VMware Horizon Log4j RCE Attempt via ws_TomcatService to cmd/powershell

Pivot detection · T1190 · 9 related

Changelog

v5
Candidate ingested via manual entry.2026-07-31
v4
Candidate ingested via manual entry.2026-07-31
v3
Candidate ingested via manual entry.2026-07-31
v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-process-creation-vmware-horizon-tomcat-service-spawning-cmd-exe-or-power-3eb91f0a

title: "Windows Process Creation: VMware Horizon Log4j RCE Attempt via ws_TomcatService to cmd/powershell"
id: 23f360e5-b205-4655-a413-046c1bd1f080
status: test
description: This rule flags process creation events where the parent process is ws_TomcatService.exe and the child process is cmd.exe or powershell.exe. Such behavior can indicate an attacker triggering initial execution from a vulnerable VMware Horizon component, consistent with attempts to achieve remote code execution through Log4j exposure. It relies on Windows process creation telemetry capturing ParentImage and Image paths.
references:
  - https://portswigger.net/daily-swig/vmware-horizon-under-attack-as-china-based-ransomware-group-targets-log4j-vulnerability
  - https://twitter.com/TheDFIRReport/status/1482078434327244805
  - https://www.pwndefend.com/2022/01/07/log4shell-exploitation-and-hunting-on-vmware-horizon-cve-2021-44228/
  - https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2021/Exploits/CVE-2021-44228/proc_creation_win_exploit_cve_2021_44228_vmware_horizon_log4j.yml
author: "@kostastsale, Huntrule Team"
date: 2022-01-14
tags:
  - attack.initial-access
  - attack.t1190
  - cve.2021-44228
  - detection.emerging-threats
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    ParentImage|endswith: \ws_TomcatService.exe
  filter_main_shells:
    Image|endswith:
      - \cmd.exe
      - \powershell.exe
  condition: selection and not 1 of filter_main_*
falsepositives:
  - Unlikely
level: high
license: DRL-1.1
related:
  - id: 3eb91f0a-0060-424a-a676-59f5fdd75610
    type: derived

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